1. Field of the Invention
The invention relates to a communication system, ports of the communication system; and a method for managing a communication system, and relates particularly to a synchronous communication system formed as a ring network of two or more ports coupled in daisy chain fashion to each other to allow communication.
2. Description of the Prior Art
A generally known communication system permits communication between nodes interconnected by a transmission line. Each node can transmit information and receive information via the transmission line. A communication system of interconnected nodes can be organized to have various topologies, such as a bus, ring, star, or tree topology, or a combination thereof.
A bus topology network is generally regarded as being linear. Transmissions from one node propagate along the transmission line and are received by all other nodes connected to a bus. A ring topology network, however, generally consists of a series of nodes connected to each another by unidirectional transmission links to form a single, closed loop. Examples of a ring network are described in IEEE 802.5 and Fiber Distributed Data Interface (FDDI).
A chosen transmission line between nodes can be either wired or wireless, for example via copper wire or fiber optics, or via a wireless transmission medium.
For real-time applications or for transferring synchronous streaming data, a communication system must have low latency and low transmission overhead. In addition, it is often necessary to synchronize clocks between nodes, and further to provide a time reference for all nodes.
U.S. Pat. No. 5,907,685 discloses a method of time synchronization between network nodes, based on extensive bidirectional communication. Such bidirectional communication imposes a significant load on the network when performed regularly at short intervals. Furthermore, significant computing power is required for evaluating communicated data.